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VATIS Update Waste Management . Nov-Dec 2005

VATIS Update Waste Management is published 4 times a year to keep the readers up to date of most of the relevant and latest technological developments and events in the field of Waste Management. The Update is tailored to policy-makers, industries and technology transfer intermediaries.

IN THE NEWS

China approves MSW destruction technology

Biosphere Development Corp., a subsidiary of the Bahamas-based Global Environmental Energy Corp., stated that its Biosphere ProcessTM system has been allowed for use in China. The China Environmental Protection Industry Association, or CEPIA, approved Biosphere process as a practical and feasible method that fulfils Chinese directives for the destruction of MSW and recycling of valuable resources. Therefore, the Shenzhen branch of Yankuang Group Co. Ltd., Shenzhen Rayes Group Co. Limited and Biosphere Development Corp. can now begin installing and operating Biosphere Process systems in China, as per the conditions of the Cooperation Framework Agreement, which the parties signed and exchanged on 27 August 2005.

The Parties have chosen Shenzhen, Yantai and Guiling to establish three to five Biosphere Process units by 30 June 2006 and a minimum of 30 Biosphere Process units before 31 December 2006. The parties have agreed to build no less than 1,300 units of this waste treatment system in China within five years.

Recyclability of plastics will force design changes

In the wake of the new waste from electrical and electronic equipment (WEEE) directive, which came into effect recently, original equipment manufacturers (OEMs) would now be compelled to introduce design changes to their products. As such, plastic producers will have to adapt to these modifications. This latest legislation, which is all about the collection and recycling of waste, means that producers of electrical and electronic equipment (EEE) will now have to finance the end-of-life recycling and recovery costs of all their products. As a result, to ensure long-term financial savings, OEMs are expected to change the design of the components they order from plastic producers.

According to Frost and Sullivan, a growth consulting company, among the many repercussions of design changes, there will be a gradual reduction in the variety of plastics used in products. A wider range of plastics makes recycling difficult and expensive owing to the separation involved before shredding. Thus, a gradual narrowing of the plastics used and possible standardization of grades are predicted in the long term, once collection and recycling have started. Plastics such as polypropylene could find greater application, as it is easy to modify them to cover a wide range of properties, thereby reducing plastics usage in appliances. Plastics that are easier to recycle will have better value.

China wakes up to electronic pollution

Chinas environmental watchdog agency has voiced concerns over the nations capability to clean-up electronic pollution, as the country dumped roughly 1.11 million tonnes of electronic waste from trashed home appliances and computers. We are under increasing pressure to clean up electronic pollution, said Mr. Zhong Bin, an official with the State Environmental Protection Administration. Every year, China disposes off at least five million TV sets, four million refrigerators, five million washing machines, another five million computers and millions of cell phones, government statistics have revealed.

Health experts say appliances and e-wastes contain toxic elements like lead, mercury and cadmium that are extremely harmful to humans and the environment. China plans to enforce regulations governing the handling of discarded electrical and electronic equipment this year. The new regulations will hold producers responsible for collection, recycling and reuse of the product wastes.

Largest electronic waste processing centre in China

Northern Chinas largest electronic waste processing and recycling base is scheduled to be set up at the new Taiding (Tianjin) Sci-tech Environment Protection Co., which is taking shape in Tianjin Economic-Technological Development Area Industrial Chemical Zone. The new facility can process up to 30,000 t/y of electronic wastes. In future, all wastes from Tianjin, and even those from northern China, will be shipped to this centre to make hazardous materials environmentally friendly and to recycle waste. Wastes from industries and household appliances comprise approximately 50 per cent of the total 30,000 t/y of electronic waste produced in Tianjin.

The electronic waste processing centre will process various kinds of electronic wastes, such as disposed of electronic chips and other components, computer motherboards, cables and wires. The centre will also separate precious metals like gold, silver and palladium as well as extract other industrially useful metals like copper, zinc and iron from the feed-in waste. Following waste de-metallization, the mixture of chips, boards and cables are processed further to yield raw materials that meet the utilization standards of the electronics sector.

Waste minimization campaign in public and private markets

In the Philippines, the Department of Environment and Natural Resources (DENR), through its Environmental Management Bureau (EMB), has inked a pact with associations of market vendors in Metro Manila to minimize solid wastes generated by public and private markets. A memorandum of agreement, which provides for intensified campaigns to raise the awareness of market vendors, buyers and other sectors on the proper management of solid wastes in wet markets (particularly on the usage of plastic bags) was signed recently at the Agora Market in San Juan between DENR-EMB and twelve associations of market vendors from Quezon City, Makati, Manila and San Juan.

Proper handling of hospital wastes

The Department of Environment and Natural Resources (DENR) and the Department of Health (DOH), the Philippines, have unveiled a DENR-DOH Joint Administrative Order that stipulates standards and procedures to be followed by hospitals and other healthcare facilities with regard to handling as well as the disposal of biohazardous wastes. The order was signed on 24 August this year at the DENR office in Quezon City. Studies reveal that about 47 t/d of hospital waste is generated in Metro Manila alone. This figure could reach 55 t/d by 2010.

System to improve recycling facilities

In the Republic of Korea, the Ministry of Environment (MOE) has laid down a guiding and inspection facility system for recycling plants chosen in August 2005. This system will focus on improving management systems on the criteria of recycling and sustainable development of the recycling facilities. By guidance and inspection, MOE seeks to achieve better and inspiring outcomes in terms of activating recycling system, revising structure that satisfy the financial requirements and raising overall outcome.

MOE will also strive to adopt this system in public institutions, multi-utilized facilities and large-scale project areas. Especially, areas like rest places, bus terminals, parks and amusement parks would be earmarked for this purpose. Large-scale project areas such as big working buildings, condos, hotels, shopping malls, supermarkets and schools will also be audited by the system.

Korea standardizes VOC content in paint

The Ministry of Environment (MOE), Republic of Korea, has established a standard for the content of volatile organic compounds (VOCs) found in paint. Scheduled to enter into force in July 2006, the VOC content standard was set up for low-VOC eco-friendly paint, which contains 5-7 per cent less VOC than existing ones, to be supplied.

The newly established standard is applicable to paint utilized in car painting and construction, which presently generate about 41 per cent of the total VOC emissions in metropolitan area. VOCs not only cause ozone pollution, but affect respiratory organs in humans and cause a nerve disorder. Furthermore, benzene and toluene were identified, among 37 kinds of VOCs, as cancer-causing substances. The standard is expected to lower VOC emissions by 8,000 t in 2006 and 20,000 t from 2006 onwards.

MOE will further reinforce the content standard of VOCs in paint in order to increase the use of low-VOC, hi-solid paint. Ultimately, it plans to replace the use of fat-soluble paint with water-soluble alternatives. In addition to this effort, MOE plans to create demand for low-VOC paint from users to lower VOC emissions while painting. In this regard, MOE will disseminate information on low-VOC paint and also offer incentives.

Accord to promote recycling of beverage cartons in Malaysia

Tetra Pak Malaysia and Singapore (TPM&S), Pascorp Paper Industries Bhd and Alam Flora Sdn Bhd have signed a Memorandum of Understanding to facilitate the introduction of beverage cartons recycling in Malaysia. As per the terms of the pact, Alam Flora will buy beverage carton wastes from the public and send them to Pascorp for recycling.

According to TPM&S Managing Director, Mr. Peter Jhaveri, TPM&S was not able to launch the recycling programme earlier as paper mills were hesitant to embrace beverage carton recycling due to the lack of awareness. Secondly, TPM&S was looking for a partner to assist us in the collection process. We now have Pascorp and Alam Flora. The Chief Executive Officer of Alam Flora, Mr. Mohammed Siraj Abdul Razack, said the collaboration would benefit the company as 50 per cent of the landfill in Alam Floras control have reached their maximum capacity or would do so by the middle of next year. With this initiative, we can now save 804 million TPM&S cartons a year from ending up in landfills, he said. Pascorps Assistant General Manager, Mr. Daniel Lew, said the company would recycle the fibre in beverage cartons into box boards while the poly-aluminum residuals would be made into panel boards for use in the furniture industry.

India moots e-waste recycling plants amid rising concerns

The downside to IT boom is being felt by an increasingly large number of people in many countries, with awareness growing regarding the detrimental activities of the human species on the environment. In India, e-waste is a major concern for the Ministry of Environment and Forests. The Central Pollution Control Board (CPCB) is anticipated to come out with a policy on e-waste in the not too distant future. Plans are underway to set up e-waste recycling plants in Delhi, Hyderabad, Mumbai and Pune.

Generally, e-waste consists of such obsolete devices as floppies, CDs, DVDs, tapes and electronic parts, including chips, processors, mother boards, printed circuit boards and industrial electronics. Experts report these wastes contain many toxic components like heavy metals, PVC plastics, brominated flame retardants, etc. For lack of a recycling facility, such wastes have to be sent to landfills, said Mr. Gopal Krishna of Toxics Link. In Bangalore, a non-government initiative known as Eparisara is conducting small-scale experiments to develop eco-friendly solutions for e-waste disposal.

Companies to lower GHG emissions

In the Republic of Korea, energy-intensive companies are expected to speed up plans for decreasing greenhouse gas (GHG) emissions, in response to the governments offer of benefits for voluntary emissions reduction. In an effort to motivate companies to launch GHG cutback initiatives, the Korean Ministry of Commerce, Industry and Energy (MOCIE) has published a draft on the registration and management of businesses to curb GHG emissions. According to the draft, companies in energy-devouring sectors e.g. mining and manufacturing, oil and gas, and thermal power generation will be required to register plans to curtail GHG emissions with the Korea Energy Management Corp. (KEMCO). An affiliate of MOCIE, KEMCO will monitor the progress of the submitted plans.

In order to be eligible for government incentives over the GHG emission reduction plans, companies should provide plans to lower at least 500 t/y of carbon dioxide emissions, beginning in October this year. The new initiative is part of the nations first-stage preparation to comply with stipulations laid down by the Kyoto Protocol. According to the protocol, advanced countries are required to cut down GHG emission levels.

Waste recycling in Pakistan

An estimated 47,920 t/d of waste is generated in Pakistan. Of this, about 53.6 per cent is gathered while the rest are left scattered around. Roughly 1 kg/person of garbage is produced and disposed of daily. As such, a city with 100,000 denizens generates 100 t/d of garbage with almost 50 per cent moisture content. The severity of garbage disposal problems is proportional to the ever-increasing population and expansion of cities.

Different strategies like incineration, sanitary landfill and recycling are available to dispose of/reuse wastes produced by human activities. A key solution to lower the huge piles of organic wastes and convert them into a useful product is composting, i.e. controlled decomposition and appropriate stabilization of blended organic substrates under aerobic conditions that allow the development of thermophilic temperature as a result of biologically produced heat. The end product of composting (compost) holds primary value as fertilizer and, secondarily, improves physical and microbial soil traits.

The effectiveness of organic wastes in sustainable crop production can be enhanced by enriching them with different nutrients, biologically active substances (such as L-tryptophan, indole-3-acetic acid, ACC, kinetin and gibberellins) and plant growth promoting rhizobia (PGPR). PGPR is capable of producing physiologically active auxins that may have pronounced effects on plant growth and development enhanced cell division, cell enlargement, vascular tissue differentiation, root initiation, apical dominance, leaf senescence, leaf and fruit abscission, fruit ripening, tropistic responses and flowering. Series of experiments that the Institute of Soil and Environmental Sciences conducted on maize and other cereal varieties have demonstrated that enriched compost (25 per cent nitrogen in the form of urea) and 50 per cent of recommended nitrogen fertilizer treatments raised growth and yield parameters such as plant height, root length, fresh biomass, fresh straw weight, grain yield, etc.

PLASTIC WASTES

PET recycling

Traditionally, post-consumer PET bottles have been recycled for use in textiles, carpets, yarns, sheets, etc. However, for economically viable recycling of PET, it is now imperative to develop new high-value-added applications and processing technologies. One such solution is being offered by UOP Sinco s.r.l., Italy. In the proprietary SSP-R process, amorphous feed chips/flakes that enter a crystallizer is de-dusted, heated and crystallized inside a multi-zone fluid bed heat exchanger. Next, these crystallized chips are conveyed to a mass flow reactor, where the intrinsic viscosity is uniformly increased to the desired level. This post-polycondensation reaction generates by-products, such as acetaldehyde, ethylene glycol and oligomers, which are removed using a nitrogen carrier gas. When the reaction is over, chips exit the reactor into a fluid bed cooler where the products temperature is lowered to the desired level.

The entire process takes place in an inert nitrogen atmosphere, to protect the product from oxidative degradation. Benefits offered by the process include:

High quality: The product has excellent resin colour, and the PET quality is on par with virgin PET, with low COOH and AA contents;

Flexibility: Post-consumer and industrial wastes can be processed;

Low-cost: The three-stage processing module with only minimal equipment ensures low investment and operating costs; and

Plastic waste used in road construction

A chemistry professor at Thiagarajar College of Engineering, India, has developed an eco-friendly method to recycle plastic shopping bags. Prof. R. Vasudevan states that the non-biodegradable eyesore when mixed with bitumen, the main ingredient of road construction, makes stronger roads that remain in their prime form for twice the period as normal asphalted roads. The plastic roads, as Prof. Vasudevan terms them, mainly use plastic shopping bags and disposable cups gathered from garbage dumps as an important ingredient of the construction matrix. When mixed with hot bitumen, plastics melt to form an oily coat over the aggregate. This mixture is laid on the road surface akin to normal asphalting of roads.

Plastic roads would be a boon for the hot and extremely humid climate in India, where temperatures often near 50C and torrential rains create havoc, leaving most of the roads with big potholes. By mixing plastic with bitumen, the latters capability to bear high temperatures increases. Bleeding usually takes place when temperatures reach 45-50C. However, when plastic is added, bitumen can retain its stability even at 55C, says Prof. Vasudevan.

New technique for tyre recycling

Atlas Polytech Inc., Canada, offers a tyre recycling process that yields moulded products. The proprietary technology does away with the need for many of the size reduction and sorting steps essential in currently available processes. According to Atlas President, Mr. Martin Scholler, the company offers two arrangements to entrepreneurs interested in adopting Atlas manufacturing process. We work in technology transfer for a small percentage of the sales or in a partnership where we too invest our own funds in return for earnings, stated Mr. Scholler.

Benefits of Atlas Polytech system include: speed of the process and the advantage of securing orders for moulded products in advance to guarantee an end market for scrap tyres or shreds taken into inventory. Additionally, the moulding process requires no curing and the products can also be made using a blend of materials, including recycled rubber, plastics as well as blends of these two materials.

Recycling strategies

Johnson Controls, a supplier of automotive interior systems, electronics and batteries, is introducing two material recycling processes that will eliminate thermal processing of 480 t/y of production wastes. The first process involves the reuse of punching waste amassed during the production of seat back panels for luxury vehicles. The cleaned scrap is crushed and blended with polypropylene pellets and processed as injection moulding components. Recycled natural fibre material is also used to manufacture armrests, utilizing recycled production waste generated during the manufacture of the door panel substrate of an executive segment automobile. A material recycling process has also been developed for glass reinforced plastics such as those employed in instrument panels.

Mobile disposal plant for medical waste

A new system for loading, reducing and sterilizing medical wastes is being offered by Aegis Bio-Systems LLC., the United States. The portable unit includes a frame supporting a sealed containment chamber, lift assembly, a hopper mounted on the frame near the lift (in communication with a material feeder), a first grinder in communication with the material feeder, a first conveyor positioned to receive medical waste from the first grinder and a second grinder, which communicates with the first conveyor. Furthermore, a second conveyor is positioned to receive waste from the second grinder and an autoclave included for thermally disinfecting the waste, mounted on a frame in the containment chamber and linked to the second conveyor assembly.

The autoclave includes a plurality of steam inlets, a waste inlet and a waste outlet for discharging waste to a third conveyor assembly. The latter conveys waste collected from the autoclave to a disposal container. The system also includes a steam generation plant mounted on the frame in the containment chamber and in communication with steam inlets of the autoclave. Website:

BIOMEDICAL / HEALTHCARE WASTES

Mobile disposal plant for medical waste

A new system for loading, reducing and sterilizing medical wastes is being offered by Aegis Bio-Systems LLC., the United States. The portable unit includes a frame supporting a sealed containment chamber, lift assembly, a hopper mounted on the frame near the lift (in communication with a material feeder), a first grinder in communication with the material feeder, a first conveyor positioned to receive medical waste from the first grinder and a second grinder, which communicates with the first conveyor. Furthermore, a second conveyor is positioned to receive waste from the second grinder and an autoclave included for thermally disinfecting the waste, mounted on a frame in the containment chamber and linked to the second conveyor assembly.

The autoclave includes a plurality of steam inlets, a waste inlet and a waste outlet for discharging waste to a third conveyor assembly. The latter conveys waste collected from the autoclave to a disposal container. The system also includes a steam generation plant mounted on the frame in the containment chamber and in communication with steam inlets of the autoclave. Website:

Disposal system organizes on-site handling of waste

French Technology Press Office Inc. has introduced Ducamp waste handling and disposal system for hospitals. The new disposal system offers turnkey solutions by studying and organizing waste management needs on-site, right from bedside collection to final disposal. It features a bar code that is applied to each filled container for identification and tracking. Furthermore, the system incorporates a new decontamination process that replaces conventional incineration of infectious material.

To optimize efficiency, the waste collection vehicle is equipped with a weighting system and a complete supply of disinfected containers to replace filled ones. Detailed track records can be printed out when required. Once the waste arrives at the decontamination facility, it undergoes high-temperature autoclave sterilization treatment. This process decontaminates the waste, which is then shredded and prepared for permanent disposal.

On-site medical waste management and disposal

Global Finest Technologies, based in Australia, is offering a single-step automated solution for sterilizing and powdering all varieties of clinical/medical wastes. The completely on-site processing reduces the waste volume by up to 80 per cent. Residue obtained after processing is sterile and unrecognizable. Up to 135 kg/h of wastes can be processed by the patented system without producing any objectionable effluents or odours and is extremely cost-effective.

The patented system comprises a jacketed pressure/vacuum vessel in to which infectious (red bag) waste is loaded. Knife hammers fitted inside the vessel rotate at speeds up to 3,500 revolutions/min to break up and shred the waste while live steam is injected to raise the temperature to around 132C. The violent knife action brings every waste particle in immediate contact with the steam-rich atmosphere and eliminates cold spots, while drastically shortening the time required for the sterilization. Once sterilization parameters have been achieved, the vessel is vented through a condenser and filter. The average process requires less than 15 minutes/cycle.

Apparatus and process for treating medical wastes

ABB Sanitec Inc., the United States, offers a new process and apparatus to treat medical hazardous wastes. The end product of this process is similar to domestic refuse and can be removed or disposed of or even supplied for recycling after sorting.

In the ABB method, infectious refuse is passed through a chamber fitted with a plurality of microwave sources located next to each other and the refuse subjected to disinfection. For safe and reliable decontamination of medical wastes in an eco-friendly and economical way, the apparatus integrates a microwave chamber as well as temperature maintenance chamber. A dense microwave field in the microwave chamber heats the refuse to/above a desired minimum temperature. Connected to the outlet of the microwave chamber is the temperature maintenance chamber.

In the microwave chamber, moist or moistened granulated refuse is heated directly by the microwaves, thus achieving rapid heating of the granulated material to the boiling point of water. The associated steam formation and steam flow increase the heating therewith through indirect warming. Especially in the case of a refuse-specific material with poor thermal conductivity e.g., plastics this results in a substantially faster and economical heating of the refuse load. In order to improve uniform temperature distribution over the cross-section of a certain layer thickness, the conveying device may be constructed as a microwave field distributor in the form of a shaftless metal conveying screw.

Microwave reflection from the walls of the microwave chamber can be achieved by building the same as a metallic U trough. Finally, to avoid heat losses, the microwave chamber could be insulated thermally and possibly have a back-up heating system.

Disposal device for medical waste

The United Kingdom-based Balcan Engineering Co. has developed a manually operated device to safely dispose of hypodermic needles and syringes. The redesigned Hypodermic Needle and Syringe Destructor meets World Health Organization stipulations, says the manufacturer. Up to 200,000 needles can easily be destructed by this model before it requires maintenance or sharpening. The device chops needles into pieces and extracts the nibs from syringes, rendering them unusable.

Electron beams help treat medical wastes

ScanTech Sciences LLC, the United States, has developed STS 10/X electron beam systems to provide extremely effective, cost-efficient and environment-friendly treatment of medical wastes. Using the same 10 MeV modular technology and hardware, ScanTech systems can treat over 454 kg/h of infectious wastes. The 10 MeV electrons have adequate energy to assure optimal penetration for all these applications. Additionally, the STS 10/X is available in modules each producing 10 kW that can be coupled for optimal throughput and economy. STS 10/X is designed to comply with the explicit and implicit requirements of each of the following issues:

Safety: The STS 10/X conformal shield is optimized for each set-up to ensure savings in installation and economic operation. An automated control system monitors all crucial operating parameters through a self-diagnostic process;

Precise control of the delivered dose: The STS 10/X control system integrates all facets of the process, including the conveyor and radiation equipment. A computer monitors dose sensors and the process to ensure quality treatment. There is a continuous record of the product treatment; and

Economic operation: The STS 10/X design is based on a proven technology and uses standardized commercial sub-systems. This plan guarantees reliability and ensures availability of spare parts.

Microwaves-based disinfection system

Agile Web Inc., the United States, offers a disinfection system to render infectious medical wastes safe for disposal as municipal solid waste. The process employed combines advanced shredding technology and conventional microwave. The waste treatment equipment is housed in a steel all-weather shelter. Fully enclosed and self-contained, the 11,338 kg system can be installed outdoors. A single electrical main connection rated at 150 amps/480 V, 3-phase, and one water hook-up are required.

A lift/charging system tips wastes into a hopper at the top of the unit. Waste material in the hopper is broken down by a rotating feed arm and ground into small particles by a shredder. Shredded particles are automatically transported into the treatment chamber, where each piece is subjected first to steam and later heated by four microwave generators, each with a HF output of 1.2 kW. The waste is heated to 95-100C and maintained at this temperature for a minimum treatment time of 30 minutes. Sensors and microprocessors control the whole procedure, ensuring proper treatment time and temperature.

Validation tests have proven that the unit achieves consistently high levels of disinfection without harmful air emissions or liquid discharges of any kind.

System to eliminate pathological wastes

Sterile Technology Industries Inc., the United States, has introduced a waste treatment product that eliminates pathological wastes on-site without incineration. STI Path-Clav 2000 treats pathologic wastes by alkaline hydrolysis. It kills all pathogens and yield an effluent safe for municipal sewers, eliminates radioactively contaminated tissues and animal carcasses, and produces no air emissions. STI Path-Clav 2000 is designed to process up to 90 kg of waste per cycle and can be left unattended during operation.

PERSISTENT ORGANIC POLLUTANTS

Treating dioxins and PCBs in solid wastes

Under a project of New Energy and Industrial Technology Development Organization (NEDO) in Japan, two technologies have been developed for the destruction of PCBs and dioxins that cling to solid wastes. One technology is for removal of dioxins present in fly-ash. It involves dioxin extraction with supercritical carbon dioxide, concentration by adsorption and then destruction by supercritical water oxidation (SCWO). The second technology is a hybrid SCWO method to treat solid wastes contaminated with PCBs. This process comprises two reactors a vessel type batch reactor and a tubular type continuous flow reactor and is suitable for the treatment of relatively high-concentration toxic substances like PCBs. Benefits of this process include:

Solid wastes can be fed without converting them into a slurry; and

Large quantities of organics can be fed into the first batch reactor, as oxygen is not supplied until the first reactor effluent is discharged.

Soil detoxification

M&S Engineering and Manufacturing Co. Inc., the United States, offers process technology and equipment for detoxifying soils containing low melting point mineral compounds with combustible toxic materials as impurities. The soil particles are heated without melting the mineral compounds to obtain combusted solids and a mixture of mineral dust and toxic material containing gas.

Combusted solids are separated from the dust-gas mixture; the dust gas mixture is thereafter segregated into mineral dust and toxic material-containing gas, which is combusted at high temperatures to form less harmful combustion products. The mineral compounds may be those of oxygen, silicon, calcium, iron and aluminium, such as oxides of these metals. Examples of combustible toxic materials are dioxin and PCB.

Post-combustion dioxin control

In the United States, researchers at the University of Dayton Research Institute have developed a simple technology to control combustion emissions. Incineration of hazardous and municipal wastes gives rise to emissions of toxic combustion by-products such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and other chlorinated hydrocarbons. Air pollution control devices (APCD) which simply remove the pollutant are not the answer as they are only transferring the pollutant from one medium to another. The need of the hour is a true destructor that can operate as a downstream APCD in a safe and economical manner.

Daytons technology is based on the concept of high-temperature photochemistry. Results from an ongoing research programme have proved that the rate of photochemical reactions of pollutants, like chlorinated hydrocarbons, can be raised from 10 to 10,000 times using moderate heating. Information gained from the research programme has led to the design of a Thermal Photolytic Destructor (TPD) that employs medium-pressure, high-energy mercury arc lamps and operates at temperatures between 300-600C.

TPD is suitable for many industrial process operations, specially those bearing halogenated hydrocarbons at mildly elevated temperatures. Nevertheless, the most immediate application is the control of dioxins from combustion sources.

Contact: The University of Dayton Research Institute, 300 College Park, Dayton, Ohio, United States of America. Tel/Fax: +1 (937) 2292 113/888

New process to treat polychlorinated biphenyl pollution

Asbestos Recycling Inc. (ARI), the United States, has developed a new thermochemical process that mineralogically converts any asbestos-containing material (ACM) polluted with polychlorinated biphenyls, or PCBs, into an inert and stable non-hazardous material. ARI is partnering with Puget Sound Naval Shipyard to demonstrate this process for the Navy. The thermochemical technology, endorsed by the United States Environmental Protection Agency (EPA), is a cost-effective and environmentally feasible alternative to landfill disposal. The PCB-ACM conversion system complies with all requirements stipulated by the National Emission Standards for Hazardous Air Pollutants (NESHAP) for asbestos conversion processes (40 CFR 61.155) and complies with (29 CFR 1910) OSHA Health and Safety Standards.

The PCB-ACM destruction unit is contained within two transportable trailer units, about 45 feet long. The operations trailer is a negative air chamber vented via HEPA filters. A secondary combustion chamber and afterburner are housed in a separate trailer. This first-generation prototype will exemplify the capabilities of the technology and provide additional data to help develop and construct permanent, modular units for nationwide implementation. Projections indicate that up to 408 kg/h of PCB-ACM can be processed by this unit.

Contaminated solids, liquids and soils are fed into the incinerators combustion chamber, which initially comprises a bed of preheated sand. A forced-air current is maintained in the bed (fluid bed) so that matter fed into the combustion chamber is immediately sucked inside. The turbulence to which contaminates are subjected in the chamber and the kiln temperature (approximately 950C) allow destruction of organic constituents like PCBs, which are found in the contaminated material. The system functions 24 h a day and does not produce either wastewater or sludge.

The technology is designed to treat 500 to 5,000 kg/h of contaminated material (including clay matrix). The CFBC unit can destroy hazardous wastes at a destruction and removal efficiency exceeding 99.9999 per cent. The CFBC conforms to and even surpasses emission norms set by the United States Environmental Protection Agency, Canadian federal regulations and Quebec guidelines and regulations. Advantages of the CFBC system over other thermic systems include:

Degradation of PCBs

Advanced Refinery Technology, the United States, has developed a new method to degrade polychlorinated biphenyls (PCBs). PCBs chemically degrade on contact with a Lewis acid catalyst. Degradation is carried out in the presence of a cation, which combines with chloride ion liberated by the degradation of PCBs to form a solid precipitate that can be removed. The procedure can easily be performed on PCBs in solution in a wide range of concentrations, including trace amounts, allowing full recovery of the bulk of the solution free of PCBs. The process may be incorporated in batch, continuous or semi-continuous processes.

Accelerated solvent extractor

Environmental analysis of soil for pesticides, semi-volatile organics (SVOCs), polychlorinated biphenyls (PCBs) and herbicides traditionally require solvent-intensive processes like Soxhlet extraction or sonication. The United States Environmental Protection Agency has approved Accelerated Solvent Extraction, or ASE, as an acceptable method for the extraction of such compounds from solid matrices. ASE is a fully automated system that requires far smaller quantities of solvent than traditional procedures. Also, ASE allows for the use of less hazardous solvents like acetone and hexane in place of methylene chloride.

A 10-30 g sample is mixed with a drying agent (e.g. sodium sulphate), placed in the extraction tube, heated and the solvent extracted. Extract thus obtained is transferred to a 60 ml vial for further concentration and analysis. The extraction procedure is performed at elevated pressure and temperatures to minimize the volume of waste generated. Since ASE extractions are carried out at pressures greater than 1,000 psi, solvents can be heated to reach temperatures far in excess of their normal boiling point. This results in much more efficient extraction.

The ASE200 is able to completely extract samples within 20 minutes and final solvent volumes are less than 50 ml. Additionally, because of increased efficiency in extraction, hexane can frequently be used for extraction and as such no solvent exchange is required. Further waste minimization is feasible since the ASE200 needs less glassware and sample extract drying. About 500 ml less solvent per sample will be used and collected for disposal.

SOLVENT

Plant to reclaim waste solvents

Bauer Environment Groups Filter-und Wassertechnik (FWS) GmbH, Germany, has developed a waste air solvent recovery plant. The self-contained plant comprises two activated carbon containers (filter beds), a steam stripping stage and a drying phase. The polluted air stream is passed through both filter beds in succession. The filters are fed with superheated steam to desorb the impurities. The steam/contaminant mixture is condensed and treated. Activated carbon can be recycled by drying and cooling.

Solvent purification

Vacuum Atmospheres Co. (VAC), the United States, offers Dri-Solv system that allows for quick and easy access to anhydrous solvents of high purity. In this patent-pending system, solvents are continuously circulated via a factory-conditioned purification cartridge and a stainless steel reservoir. The purification cartridge is easily replaced with drip-free quick release connections.

A compact footprint (28 10 10 inch) facilitates the system to be mounted inside a fume hood or on bench-top. Designed to accommodate a four-litre solvent bottle, the VAC system eliminates the need to store large quantities of unstable solvents and reduces the potential wastage of large amounts of solvent owing to the accumulation of contaminants, such as peroxides. VAC recharges the reusable/returnable cartridge at a nominal cost.

Improvements provided by the Dri-Solv system over traditional varieties of Grubbs type solvent purification are due to the properties of dynamic, multiple-pass flow vs. a single pass static design. VACs dynamic flow optimizes catalytic performance by enhancing contact with the available surface area of activated getter materials. Performance is further raised by the cumulative results of multiple cycles through the purifier cartridge. Dynamic flow and multiple-pass method also increases overall effective capacity of the cartridge materials. Improved use of better material capacity lowers the amount of solid waste generated by VACs process vs. the traditional Grubbs procedure or distillation.

Paint-thinner solvent recyclers

Uni-Ram, Canada, is offering Encore solvent recyclers that convert waste solvents into savings. These devices save money, lower waste disposal costs and potential liabilities. Easy and cost-effective to operate, the recyclers are available in two models (URS500 and URS900) approved by CETL, an accredited testing facility, to be Explosion Proof under CSA 22.2-30 as well as other applicable standards for Class 1, Division 1, Group D. Ideal for appliance, furniture painting, bodyshop, printing and dry cleaning locations, key benefits of the recyclers include:

Acetonitrile recovery from waste solvent

Standard Oil Co., the United States, is offering a process to treat waste solvent acetonitrile streams containing at least one water extractable impurity isopropyl acetate. All of the impurity can be substantially removed by distilling the waste solvent acetonitrile in the presence of water for a time sufficient to allow the water extractable impurity to be extractively distilled from acetonitrile. The invention is applicable with feeds that contain either a mixture of the waste solvent acetonitrile and crude acetonitrile, or crude acetonitrile free of hydrogen cyanide by itself.

INDUSTRIAL WASTEWATER

Removal of heavy metal from industrial wastewater

Researchers at Universiti of Tenaga Nasional, Malaysia, embarked on a study to interpret the biosorption process and then develop a cost-effective technology to treat heavy metals-containing industrial wastewater. A new composite biosorbent was prepared by coating chitosan on to acid-treated oil palm shell charcoal (AOPSC). Chitosan loading on the AOPSC support is about 21 per cent by weight. The shape of the adsorbent is nearly spherical, with particle diameter in the range of 100~150 m.

Results have shown that the use of chitosan-coated AOPSC for removal of chromium ions is environment- friendly, technically viable and quite efficient. Moreover, being composed entirely of agricultural and fishing industry waste, it helps in reducing waste generation. The adsorbent can be regenerated using sodium hydroxide and as such can be reused. This adsorbent can be a good candidate for adsorption of not only chromium ions but also other heavy metal ions in wastewater stream.

Oxidation of reactive blue dye wastewater

Pre-ozonation has been found to be effective in decolourizing and raising the biodegradability of textile dye wastewater while lowering pollution load. However, the cost of ozonation is high due to poor gas-liquid mass transfer and self-decomposition reactions. Ozonation efficiency can be increased by in situ generation of ozone and reacting it immediately with the wastewater contaminants.

In the United States, researchers at Kansas State University have developed a novel porous electrode system for the generation and reaction of ozone with contaminants in aqueous phase. The in situ ozone generator is based on a novel type of corona discharge tube design, wherein the discharge gap is kept juxtaposed to the tubular pathway through which the treatment fluid is passed. Ozone is generated around the periphery of the porous electrode tube and diffuses immediately into the contaminated fluid flowing inside the tube. The inner porous ceramic tube is grounded and the outer glass electrode positively charged to enable corona discharge.

Biological process for nitrogen removal

Several nitrification/denitrification methods are available for ammonia and nitrate removal from municipal and industrial wastewater. There are, however, few such methods for the removal of these ions from metal-processing and finishing wastewater. Researchers at Rhodes University, South Africa, examined a biological process for this purpose. The system comprises an aerobic continuously stirred tank reactor (CSTR) followed by an anaerobic packed column. It was tested using wastewater effluent of a metal-processing operation. The proprietary system was inoculated using humus sludge from a municipal trickling filter, and a period of approximately four weeks was required for a denitrifying biofilm to develop.

Results have shown that ammonia removal occurs readily in the CSTR while nitrite oxidation was slower to develop. The CSTR was found to be suitable for ammonia oxidation: up to 89 per cent ammonia removal was achieved. The gravel-packed column reactor was not found to be suitable for nitrate removal in the configuration used (maximum 15 per cent removal efficiency). Critical parameters for denitrification include nitrate concentration, temperature, mean cell retention time and influent flow rate.

Advanced treatment for textile wastewater

In China, researchers have studied a method that integrates electrochemical oxidation and membrane filtration to treat wastewater from the textile industry. The team employed a modified transfer-flow membrane (TFM) module, with fibres welded in an arc shape to raise mechanical properties of the fibres as well as enhance the TFM modules specific membrane surface. The research focused on evaluating performance of the arc-shaped TFM module to demonstrate these sequences of electrochemical oxidation coupled with membrane filtration processes and to develop a potential dye-house wastewater treatment system.

Two testing sequences of electrochemical oxidation and membrane filtration were studied in a sequential batch order. Results have shown that fibres welded in an arc shape enhance the mechanical properties of the fibres effectively. Also, electrochemical oxidation and membrane filtration are feasible as sequential methods. Electrochemical oxidation has high removal efficiency (89.8 per cent) of the wastewaters chemical oxygen demand (COD), while the membrane filter can almost totally nearly 100 per cent reduction remove the total suspended solids (TSS) and turbidity (98.3 per cent elimination) in it.

Wastewater treatment plant for electronics industry

The chemicals used by each printed circuit board (PCB) shop differ. As such, each generate different liquid waste with metals and other contaminants. Kurion Technologies Ltd., the United Kingdom, offers a range of standard stand-alone technologies that can be combined to treat different types of wastewater from the manufacturing facilities.

The simplest treatment is a metal precipitation process designed to meet discharge limits. This end-of-pipe concept, the lowest capital cost option, utilizes proprietary two-step reaction system in combination with cyclone settlement technology. Limits of 1.0 ppm copper and 0.4 ppm lead are achievable. Additionally, up to 0.1 ppm copper and 0.1 ppm lead is feasible with IX polishing technology. Much more lower limits can be realized by special chemistry and waste segregation techniques.

Kurions batch treatment system or TREAT-RESIST treats other wastes such as permanganate of dry film stripper and developer dumps. Metal recovery and sludge minimization combined with guaranteed effluent compliance is feasible. Treatment of copper solution is accomplished by recirculating the fluid through an electrowinning cell, thus depositing copper on to the cathodes. Kurion has developed a plate-out cell suitable for treating a variety of spent solutions. Typically, over 90 per cent of the metal is recovered from each individual bath. Other systems from Kurion include:

IX/ER system for copper recovery from rinses and low copper ores;

The lead-resin system, a cost-effective option to treat lead bearing rinses; and

Cryomagnets for wastewater treatment

A purification system developed by Prof. Shigehiro Nishijima and others at Osaka University, Japan, utilizes cryomagnets to treat wastewater from recycled paper plants. In this process, magnetite or iron oxide particles added to the wastewater react with impurities in the waste-forming magnetic compounds. The compounds are then attracted to a stainless filter under the intense magnetic force of a niobium titanium cryomagnet when the wastewater passes through the filter. Both the size and cost of the new system are less than half that of existing units, typically based on activated sludge method.

Extracting metal fluoride from waste

R&F Co. Ltd., Republic of Korea, offers technology to recycle fluorine-containing wastewater produced by the semiconductor industry. In this procedure, a metal fluoride reactor tank is constructed as part of the existing wastewater treatment process, which produces metal fluoride through precipitation and filtration. Additional metal fluoride is obtained by eliminating fluoride ions left from the filtered water, utilizing calcium hydroxide sludge. Fluorine ion concentrations less than 3 ppm can be achieved. High-purity metal fluoride thus reclaimed could be used as a solvent for fluoride glass, a solvent for metal fluoride welding rods and as an electrode material for lithium batteries.

Treating industrial/municipal wastewater

Waterleau, Belgium, is offering a so-called hybrid system that combines the benefits of conventional wastewater treatment and SBR methods. Lucas, a cyclic activated sludge system, in its basic configuration comprises three reactors, all with a similar design and equipment. The reactors are interconnected through openings in common walls. Influent can be sent to each reactor, just as the effluent can be discharged from them individually. In each basin, the desired process environment can be created aerobic, anoxic, anaerobic or sedimentation state. Individual inlets and outlets can be automatically closed/opened. Influent is fed directly to the reactors. Each basin includes a combined feeding-and- aeration phase, an aeration phase and a sedimentation phase. Thus, each reactor is subsequently:

Fed and aerated;

Aerated; and

Not aerated in order to facilitate sedimentation.

Effluent and excess sludge are withdrawn from the reactor that is in sedimentation. The length of the phases can be adapted according to hydraulic and organic loading.

Desalination of organic wastewater

Research has been carried out in China to assess the efficacy of an evaporation crystallizer for desalinating alkaline organic wastewater. Researchers devised a wastewater evaporation-desalination pretreatment method to remove potassium (K) and sodium (Na) in wastewater that contains volatile organic compounds (VOCs) before it is passed on to the incinerator. VOCs in the wastewater volatilize in the evaporation unit and the ensuing vapours get combusted in the incinerator. In a simulation, phenol wastewater with sodium chloride (NaCl) was evaporated and concentrated, and NaCl crystallized. Results have demonstrated that the higher initial density of NaCl increases the ratio of volatilization of VOCs. This is due to the effect of salting out a fall in the solubility of the non-electrolyte in solution, or more rigorously, an increase in its activity coefficient caused by the salt addition.

When the evaporation speed was increased from 1.67 ml/min to 2.73 ml/min, total removal coefficient of NaCl was 99.88-99.99 per cent. This pretreatment eliminates slag phenomenon caused by Na and K salts during incineration of wastewater.

Purification of tannery effluent

At the University of Waikato, New Zealand, a new electrolytic effluent processor that enables purification of tannery effluents has been designed by a research team. The specialized proprietary prototype effluent processor, which is based on a novel anode design, was tested extensively and satisfactory results obtained during continuous inline operation, despite wide variation in the composition of the inflow. Over 90 per cent removal of chromium from solution, with similar reductions in turbidity, were achieved at lower operating cost, residual aluminium and total aluminium addition than by dosing with usual commercial aluminium-based flocculants such as poly-aluminium chloride.

While the system performed well under conditions of a real tannery, the mechanism of operation was difficult to discern in the field. This was due to the numerous types of compounds in the effluent and the rapidly varying absolute and relative levels of the component impurities. Particularly, the excellent results with low residual aluminium at pH in excess of 9.5 was unexpected, given the high solubility of aluminium at that pH. Also, the effect of pulsed voltage waveforms was trialed at the tannery, but any effects were swamped by the rapid variations in the effluent content.

PURONs patented module design provides reliable removal of filtered material. Hollow fibre membranes, 2 mm in diameter with a pore size less than 0.1 m, are bundled in a single header at their lower end. Each hollow fibre membrane filter is sealed at the upper end and left to float freely. The filter membrane is coated on a braid, increasing the mechanical strength of each fibre to ensure that they do not break or delaminate. Water flows from the outside to the inside of the filters. Solids and particulates, including bacteria, are blocked and remain on the outside, while the permeate is withdrawn from inside the fibres.

Reheating of treated gas and prevention of white smoke through humidity control.

Automatic control of pH level and salt concentration in the waste liquid ensure stable operation. There is no restriction of gas volume. The system can handle gas exhaust in a temperature range of 150-300C. Acid gas removal rate achieved is lower than 15 ppm for HCl and less than 10 ppm for SO2.

Selective catalytic NOx reduction

NKK Corp., Japan, offers a system for removing NOx from flue gas, to a concentration less than 30 ppm (in terms of 12 per cent oxygen). Oxygen (O2) molecule contained in the flue gas by catalytic activity is assumed as Atomic State Oxygen O (activated substance). This splits NO and NO2 (bonded molecules). The divided NO and NO2 then react with ammonia (NH3) injected in front of the catalyst to produce harmless nitrogen (N2) and steam. Reaction occurs as the flue gas passes via the catalytic layer, but the catalyst must be kept in the temperature zone (200-450C) to be active. NOx decomposition reaction is stated by the following formula:

Gas removal system

Kurabo Industries Ltd., Japan, offers KISCAM gas removal system to eliminate acid gases such as HCl and SO2. This is achieved by a full reaction of flue gas in the bag reactor precoated with alkalis. By means of a special reacting agent, harmful gas removal rate increases further. Moreover, dioxin generation reduces on account of relatively low reaction temperature (200C). Key features of the system include:

Selective catalytic NOx removal system

Miura Chemical Equipment Co. Ltd., Japan, has developed a system to decompose NOx into water (H2O) and harmless nitrogen (N2). This is achieved by employing catalysts like ammonia-based reduction agent to transform flue gases into clean gas. Key features of this system are:

Simple process of letting NOx-rich flue gas to pass through catalyst layers in the presence of ammonia (NH3), facilitating decomposition of flue gas into N2 and H2O;

Superior performance as well as reliability attained by way of catalyst selection and optimized application condition; and

Economical and non-wasteful disposal through automatic control of NH3 addition in response to flue gas load.

New scrubbing systems

Stevens Painton Corp., the United States, is offering various scrubbing systems for use in controlling air pollution. An advanced dry scrubbing system provides acid gas removal performance close to that of typical spray dryer/absorber systems. The key component of this system is a dual pass reactor, which exposes incoming gas to turbulent mixing with the alkaline reagent for a full 2.5-3 seconds. This turbulent mixing combined with a high rate of reagent recycling provides up to 85 per cent SO2 removal and 98 per cent HCl removal with Ca(OH)2. Lime use also rivals that of a spray/dryer absorber system. A high reagent recycling permits for system stoichiometric ratios in the range of 1.3 to 1.5 using hydrated lime. Dioxins/furans and mercury emissions are controlled using powdered activated carbon.

The company also offers a complete line of spray dryer/absorbers that includes a selection of Turbosonic Technologies dual fluid nozzle or rotary atomizer sprays.

Controlling VOC emissions

Alstom Power, Japan, offers Smith regenerative thermal oxidizer (RTO) that uses heat to convert harmful pollutants like VOCs, air toxicants and odours, into harmless carbon dioxide and water. Another product available from the company is the unique KEMPAK chemical scrubber for application in controlling odours from casting processes. Alstoms RTO offers:

Destruction/removal efficiency (DRE) of 95 per cent to 99+ per cent;

Efficient reuse of 80-95 per cent of waste heat;

Operation temperature ranges from 760C to over 1,090C;

Automatic control system that assures safe operation and low-cost operation; and

Easy to install and maintain.

The unique KEMPAK scrubber is a high-performance deodorization system that operates under different conditions to those of conventional technologies. Additionally, KEMPAK scrubbers are energy-efficient, with a low pressure drop under normal operating conditions.

Air purification systems

Chugai Ro Co. Ltd., Japan, offers a range of air purification systems, which include regenerative thermal oxidizers (RTOs). The single-tower, multi-room RTO makes use of the principle of heat reproduction with a ceramic thermal storage material heated and cooled alternately. The equipment demonstrates an energy-saving effect with a heat efficiency ratio of 95 per cent, in addition to a maximum deodorization efficiency ratio of 99 per cent. Furthermore, this equipment is economical and needs minimal maintenance service.

Wet scrubber

Takuma Co. Ltd., Japan, offers a wet scrubber to remove HCl, SOx, etc. present in combustion gas streams. The exhaust gas is scrubbed with water, to absorb such substances into water, which is neutralized later using sodium hydroxide and used again, except for a part that is discharged to balance the salt content. The gas is humidified and cooled by water scrubbing until it is saturated. The next stage involves contact-dehumidifying by the cooling water circulation unit to prevent the white smoke. Water-soluble mercury is removed completely from the cycling water by chemical means.

Dry exhaust gas scrubbing system

SemiAn Technology, Korea, offers the SSD200, SSD201 and SSD202 gas treatment and abatement type normal temperature chemisorption reactors for combination with semiconductor CVD, ion implant and dry etcher. A by-pass cartridge is installed for emergency treatment of exhaust gas. The temperature is detected in order to protect the scrubber against overheating by adsorption heat, and inlet pressure is measured to ensure continuous gas flow through the cleaner. The system is operated by means of a touch screen TFT monitor. Salient features include: